Branched crack growth behavior of mixed-mode fatigue for an austenitic 304L steel

Experiments on mixed-mode fatigue crack initiation and propagation in an austenitic stainless steel 304L were carried out using a circular ring specimen containing a V-notch on the internal radius. The branched crack behavior was experimentally investigated with respect to the direction of the inclined loading and the stress distribution near the notch root or crack tip, especially, for the second and third branched cracks. The behavior of the crack initiating from the notch root under the mixed-mode condition is identified well by the maximum tangential stress criterion. The energy release rate criterion can be used to simulate the path of the branched cracks initiating from the parent crack. Optical microscope observation was performed to examine the microstructure of the material for the tested specimens and all crack growth was typically transgranular mode.